全文获取类型
收费全文 | 15068篇 |
免费 | 901篇 |
国内免费 | 1727篇 |
专业分类
林业 | 1684篇 |
农学 | 2177篇 |
基础科学 | 1438篇 |
2799篇 | |
综合类 | 4523篇 |
农作物 | 876篇 |
水产渔业 | 628篇 |
畜牧兽医 | 1982篇 |
园艺 | 492篇 |
植物保护 | 1097篇 |
出版年
2024年 | 67篇 |
2023年 | 220篇 |
2022年 | 537篇 |
2021年 | 692篇 |
2020年 | 618篇 |
2019年 | 662篇 |
2018年 | 412篇 |
2017年 | 631篇 |
2016年 | 529篇 |
2015年 | 741篇 |
2014年 | 673篇 |
2013年 | 830篇 |
2012年 | 999篇 |
2011年 | 989篇 |
2010年 | 964篇 |
2009年 | 881篇 |
2008年 | 812篇 |
2007年 | 883篇 |
2006年 | 810篇 |
2005年 | 732篇 |
2004年 | 363篇 |
2003年 | 243篇 |
2002年 | 243篇 |
2001年 | 248篇 |
2000年 | 272篇 |
1999年 | 389篇 |
1998年 | 317篇 |
1997年 | 290篇 |
1996年 | 242篇 |
1995年 | 257篇 |
1994年 | 184篇 |
1993年 | 210篇 |
1992年 | 180篇 |
1991年 | 136篇 |
1990年 | 129篇 |
1989年 | 88篇 |
1988年 | 68篇 |
1987年 | 56篇 |
1986年 | 36篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1973年 | 2篇 |
1964年 | 2篇 |
1963年 | 3篇 |
1935年 | 1篇 |
1934年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
63.
不同渗灌处理方式对塑料大棚黄瓜植株生长的影响 总被引:6,自引:0,他引:6
通过不同渗灌处理方式对大棚黄瓜植株生长影响的研究结果表明:渗灌管平行于垄向、埋深35 cm(厘米)、管间距离1.2 m(米)的处理方式和渗灌管垂直于垄向、埋深35 cm(厘米)、管间距离1 m(米)的处理方式利于本地区塑料大棚黄瓜植株的生长. 相似文献
64.
65.
66.
67.
68.
Y. J. Huang C. Toscano-Underwood B. D. L. Fitt † X. J. Hu A. M. Hall 《Plant pathology》2003,52(2):245-255
Ascospores of both A-group and B-group Leptosphaeria maculans germinated at temperatures from 5 to 20°C on leaves of oilseed rape. Germination of ascospores of both groups started 2 h after inoculation and percentage germination reached its maximum about 14 h after inoculation at all temperatures. Both the percentage of A-/B-group ascospores that had germinated after 24 h incubation and germ tube length increased with increasing temperature from 5 to 20°C. Germ tubes from B-group ascospores were longer than those from A-group ascospores at all temperatures, with the greatest difference at 20°C. Hyphae from ascospores of both groups penetrated the leaves predominantly through stomata, at temperatures from 5 to 20°C. A-group ascospores produced highly branched hyphae that grew tortuously, whereas B-group ascospores produced long, straight hyphae. The percentage of germinated ascospores that penetrated stomata increased with increasing temperature from 5 to 20°C and was greater for A-group than for B-group L. maculans after 40 h incubation. 相似文献
69.
70.
Jan Fahleson Ulf Lagercrantz Qiong Hu Lisa Ann Steventon Christina Dixelius 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(4):361-371
Amplified fragment length polymorphism (AFLP) analysis was used to study genetic variation among 76 isolates of Verticillium. A dendrogram based on the AFLP data revealed three main groups. One group consisted of 35 European isolates derived from Brassica napus together with five Californian isolates taken from B. oleracea. This group displayed a high degree of genetic similarity and included three isolates earlier classified as Verticillium longisporum, indicating that all isolates in this group probably should be regarded as members of V. longisporum. V. dahliae isolates constituted the second group while the third group contained four V. albo-atrum isolates. In addition to these three groups, a cluster of six V. nigrescens isolates was observed. However, the genetic distances between the isolates of V. nigrescens were much higher than those between members in the other groups and the bootstrap value for the V. nigrescens cluster was subsequently low. Four isolates classified as V. tricorpus were highly diverse and did not cluster together. Analysis of molecular variance revealed that the isolates of V. longisporum were separated into four subgroups, based on geographic origin. The study furthermore shows that AFLP is a suitable method for studying population structure in Verticillium. 相似文献